While I very much like that there is now a statically typed programming language available on Erlang and even in the ML tradition, the downsides are that it is a very basic ML. After using OCaml for a while I kinda got used to all the ML-extensions their type system allows, so recreating an ML from scratch sounds like a lot of work if you want to have something of comparable power to OCaml which took years of work from very smart people. Whereas with approaches like jsofocaml, you get all the type system features for free and can use it on a very simple language.

Truth be told, I am not sure how difficult it would be to have a jsofocaml-like approach on the Erlang VM and whether you’d need to have some extensions to the language to have interop with Erlang. Just my thoughts when I read on this.